kvdb+lncfg: fully move etcd behind build tag

This commit separates all etcd related sources (sans a few stubs and
config) from the rest of the source tree and makes compilation conditional
depending on whether the kvdb_etcd build tag is specified.

channeldb/kvdb/backend.go

@@ -5,7 +5,7 @@ import (
 	"os"
 	"path/filepath"
 
-	"github.com/lightningnetwork/lnd/channeldb/kvdb/etcd"
+	_ "github.com/btcsuite/btcwallet/walletdb/bdb" // Import to register backend.
 )
 
 // fileExists returns true if the file exists, and false otherwise.
@@ -63,16 +63,7 @@ func GetTestBackend(path, name string) (Backend, func(), error) {
 		}
 		return db, empty, nil
 	} else if TestBackend == EtcdBackendName {
-		config, cleanup, err := etcd.NewEmbeddedEtcdInstance(path)
-		if err != nil {
-			return nil, nil, err
-		}
-		backend, err := Open(EtcdBackendName, *config)
-		if err != nil {
-			cleanup()
-			return nil, nil, err
-		}
-		return backend, cleanup, nil
+		return GetEtcdTestBackend(path, name)
 	}
 
 	return nil, nil, fmt.Errorf("unknown backend")

channeldb/kvdb/bbolt.go

@@ -1,10 +0,0 @@
-package kvdb
-
-import (
-	_ "github.com/btcsuite/btcwallet/walletdb/bdb" // Import to register backend.
-)
-
-// BoltBackendName is the name of the backend that should be passed into
-// kvdb.Create to initialize a new instance of kvdb.Backend backed by a live
-// instance of bbolt.
-const BoltBackendName = "bdb"

channeldb/kvdb/config.go

@@ -0,0 +1,33 @@
+package kvdb
+
+// BoltBackendName is the name of the backend that should be passed into
+// kvdb.Create to initialize a new instance of kvdb.Backend backed by a live
+// instance of bbolt.
+const BoltBackendName = "bdb"
+
+// EtcdBackendName is the name of the backend that should be passed into
+// kvdb.Create to initialize a new instance of kvdb.Backend backed by a live
+// instance of etcd.
+const EtcdBackendName = "etcd"
+
+// BoltConfig holds bolt configuration.
+type BoltConfig struct {
+	NoFreeListSync bool `long:"nofreelistsync" description:"If true, prevents the database from syncing its freelist to disk"`
+}
+
+// EtcdConfig holds etcd configuration.
+type EtcdConfig struct {
+	Host string `long:"host" description:"Etcd database host."`
+
+	User string `long:"user" description:"Etcd database user."`
+
+	Pass string `long:"pass" description:"Password for the database user."`
+
+	CertFile string `long:"cert_file" description:"Path to the TLS certificate for etcd RPC."`
+
+	KeyFile string `long:"key_file" description:"Path to the TLS private key for etcd RPC."`
+
+	InsecureSkipVerify bool `long:"insecure_skip_verify" description:"Whether we intend to skip TLS verification"`
+
+	CollectStats bool `long:"collect_stats" description:"Whether to collect etcd commit stats."`
+}

channeldb/kvdb/etcd.go

@@ -1,10 +0,0 @@
-package kvdb
-
-import (
-	_ "github.com/lightningnetwork/lnd/channeldb/kvdb/etcd" // Import to register backend.
-)
-
-// EtcdBackendName is the name of the backend that should be passed into
-// kvdb.Create to initialize a new instance of kvdb.Backend backed by a live
-// instance of etcd.
-const EtcdBackendName = "etcd"

channeldb/kvdb/etcd/bucket.go

@@ -1,3 +1,5 @@
+// +build kvdb_etcd
+
 package etcd
 
 import (

channeldb/kvdb/etcd/bucket_test.go

@@ -1,3 +1,5 @@
+// +build kvdb_etcd
+
 package etcd
 
 // bkey is a helper functon used in tests to create a bucket key from passed

channeldb/kvdb/etcd/db.go

@@ -1,3 +1,5 @@
+// +build kvdb_etcd
+
 package etcd
 
 import (

channeldb/kvdb/etcd/db_test.go

@@ -1,3 +1,5 @@
+// +build kvdb_etcd
+
 package etcd
 
 import (

channeldb/kvdb/etcd/driver.go

@@ -1,3 +1,5 @@
+// +build kvdb_etcd
+
 package etcd
 
 import (

channeldb/kvdb/etcd/driver_test.go

@@ -1,3 +1,5 @@
+// +build kvdb_etcd
+
 package etcd
 
 import (

channeldb/kvdb/etcd/embed.go

@@ -1,3 +1,5 @@
+// +build kvdb_etcd
+
 package etcd
 
 import (

channeldb/kvdb/etcd/fixture_test.go

@@ -1,3 +1,5 @@
+// +build kvdb_etcd
+
 package etcd
 
 import (

channeldb/kvdb/etcd/readwrite_bucket.go

@@ -1,3 +1,5 @@
+// +build kvdb_etcd
+
 package etcd
 
 import (

channeldb/kvdb/etcd/readwrite_bucket_test.go

@@ -1,3 +1,5 @@
+// +build kvdb_etcd
+
 package etcd
 
 import (

channeldb/kvdb/etcd/readwrite_cursor.go

@@ -1,3 +1,5 @@
+// +build kvdb_etcd
+
 package etcd
 
 // readWriteCursor holds a reference to the cursors bucket, the value

channeldb/kvdb/etcd/readwrite_cursor_test.go

@@ -1,3 +1,5 @@
+// +build kvdb_etcd
+
 package etcd
 
 import (

channeldb/kvdb/etcd/readwrite_tx.go

@@ -1,3 +1,5 @@
+// +build kvdb_etcd
+
 package etcd
 
 import (

channeldb/kvdb/etcd/readwrite_tx_test.go

@@ -1,3 +1,5 @@
+// +build kvdb_etcd
+
 package etcd
 
 import (

channeldb/kvdb/etcd/stm.go

@@ -1,3 +1,5 @@
+// +build kvdb_etcd
+
 package etcd
 
 import (

channeldb/kvdb/etcd/stm_test.go

@@ -1,3 +1,5 @@
+// +build kvdb_etcd
+
 package etcd
 
 import (

channeldb/kvdb/etcd/walletdb_interface_test.go

@@ -1,3 +1,5 @@
+// +build kvdb_etcd
+
 package etcd
 
 import (

channeldb/kvdb/kvdb_etcd.go

@@ -0,0 +1,48 @@
+// +build kvdb_etcd
+
+package kvdb
+
+import (
+	"github.com/lightningnetwork/lnd/channeldb/kvdb/etcd"
+)
+
+// TestBackend is conditionally set to etcd when the kvdb_etcd build tag is
+// defined, allowing testing our database code with etcd backend.
+const TestBackend = EtcdBackendName
+
+// GetEtcdBackend returns an etcd backend configured according to the
+// passed etcdConfig.
+func GetEtcdBackend(etcdConfig *EtcdConfig) (Backend, error) {
+	// Config translation is needed here in order to keep the
+	// etcd package fully independent from the rest of the source tree.
+	backendConfig := etcd.BackendConfig{
+		Host:               etcdConfig.Host,
+		User:               etcdConfig.User,
+		Pass:               etcdConfig.Pass,
+		CertFile:           etcdConfig.CertFile,
+		KeyFile:            etcdConfig.KeyFile,
+		InsecureSkipVerify: etcdConfig.InsecureSkipVerify,
+		CollectCommitStats: etcdConfig.CollectStats,
+	}
+
+	return Open(EtcdBackendName, backendConfig)
+}
+
+// GetEtcdTestBackend creates an embedded etcd backend for testing
+// storig the database at the passed path.
+func GetEtcdTestBackend(path, name string) (Backend, func(), error) {
+	empty := func() {}
+
+	config, cleanup, err := etcd.NewEmbeddedEtcdInstance(path)
+	if err != nil {
+		return nil, empty, err
+	}
+
+	backend, err := Open(EtcdBackendName, *config)
+	if err != nil {
+		cleanup()
+		return nil, empty, err
+	}
+
+	return backend, cleanup, nil
+}

channeldb/kvdb/kvdb_no_etcd.go

@@ -0,0 +1,24 @@
+// +build !kvdb_etcd
+
+package kvdb
+
+import (
+	"fmt"
+)
+
+// TestBackend is conditionally set to bdb when the kvdb_etcd build tag is
+// not defined, allowing testing our database code with bolt backend.
+const TestBackend = BoltBackendName
+
+var errEtcdNotAvailable = fmt.Errorf("etcd backend not available")
+
+// GetEtcdBackend is a stub returning nil and errEtcdNotAvailable error.
+func GetEtcdBackend(etcdConfig *EtcdConfig) (Backend, error) {
+	return nil, errEtcdNotAvailable
+}
+
+// GetTestEtcdBackend  is a stub returning nil, an empty closure and an
+// errEtcdNotAvailable error.
+func GetEtcdTestBackend(path, name string) (Backend, func(), error) {
+	return nil, func() {}, errEtcdNotAvailable
+}

channeldb/kvdb/kvdb_test_bdb.go

@@ -1,5 +0,0 @@
-// +build !kvdb_etcd
-
-package kvdb
-
-const TestBackend = "bdb"

channeldb/kvdb/kvdb_test_etcd.go

@@ -1,5 +0,0 @@
-// +build kvdb_etcd
-
-package kvdb
-
-const TestBackend = "etcd"

lncfg/db.go

@@ -4,7 +4,6 @@ import (
 	"fmt"
 
 	"github.com/lightningnetwork/lnd/channeldb/kvdb"
-	"github.com/lightningnetwork/lnd/channeldb/kvdb/etcd"
 )
 
 const (
@@ -13,42 +12,20 @@ const (
 	etcdBackend = "etcd"
 )
 
-// BoltDB holds bolt configuration.
-type BoltDB struct {
-	NoFreeListSync bool `long:"nofreelistsync" description:"If true, prevents the database from syncing its freelist to disk"`
-}
-
-// EtcdDB hold etcd configuration.
-type EtcdDB struct {
-	Host string `long:"host" description:"Etcd database host."`
-
-	User string `long:"user" description:"Etcd database user."`
-
-	Pass string `long:"pass" description:"Password for the database user."`
-
-	CertFile string `long:"cert_file" description:"Path to the TLS certificate for etcd RPC."`
-
-	KeyFile string `long:"key_file" description:"Path to the TLS private key for etcd RPC."`
-
-	InsecureSkipVerify bool `long:"insecure_skip_verify" description:"Whether we intend to skip TLS verification"`
-
-	CollectStats bool `long:"collect_stats" description:"Wheter to collect etcd commit stats."`
-}
-
 // DB holds database configuration for LND.
 type DB struct {
 	Backend string `long:"backend" description:"The selected database backend."`
 
-	Etcd *EtcdDB `group:"etcd" namespace:"etcd" description:"Etcd settings."`
+	Etcd *kvdb.EtcdConfig `group:"etcd" namespace:"etcd" description:"Etcd settings."`
 
-	Bolt *BoltDB `group:"bolt" namespace:"bolt" description:"Bolt settings."`
+	Bolt *kvdb.BoltConfig `group:"bolt" namespace:"bolt" description:"Bolt settings."`
 }
 
 // NewDB creates and returns a new default DB config.
 func DefaultDB() *DB {
 	return &DB{
 		Backend: boltBackend,
-		Bolt: &BoltDB{
+		Bolt: &kvdb.BoltConfig{
 			NoFreeListSync: true,
 		},
 	}
@@ -75,16 +52,7 @@ func (db *DB) Validate() error {
 // GetBackend returns a kvdb.Backend as set in the DB config.
 func (db *DB) GetBackend(path string) (kvdb.Backend, error) {
 	if db.Backend == etcdBackend {
-		backendConfig := etcd.BackendConfig{
-			Host:               db.Etcd.Host,
-			User:               db.Etcd.User,
-			Pass:               db.Etcd.Pass,
-			CertFile:           db.Etcd.CertFile,
-			KeyFile:            db.Etcd.KeyFile,
-			InsecureSkipVerify: db.Etcd.InsecureSkipVerify,
-			CollectCommitStats: db.Etcd.CollectStats,
-		}
-		return kvdb.Open(kvdb.EtcdBackendName, backendConfig)
+		return kvdb.GetEtcdBackend(db.Etcd)
 	}
 
 	return kvdb.GetBoltBackend(path, dbName, db.Bolt.NoFreeListSync)